Fix the field count in interface record layout (it was incorrectly

compensating for super classes). This was making the reported class
sizes for empty classes very, very wrong.
 - Also, we now report the size info for an empty class like gcc (as
   the offset of the start, not as 0, 0).

 - Add a few more test cases we were mishandling before (padding bit
   field at end of struct, for example).

llvm-svn: 70938

2 files changed, 7 insertions, 12 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index a9f13c95180..a947fea95aa 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -713,10 +713,6 @@ ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
 
   ASTRecordLayout *NewEntry = NULL;
   if (ObjCInterfaceDecl *SD = D->getSuperClass()) {
-    // FIXME: This increment of FieldCount is wrong, we don't actually
-    // count the super class as a member (see the field index passed
-    // to LayoutField below).
-    FieldCount++;
     const ASTRecordLayout &SL = getASTObjCInterfaceLayout(SD);
     unsigned Alignment = SL.getAlignment();
     uint64_t Size = SL.getSize();
@@ -729,8 +725,6 @@ ASTContext::getObjCLayout(const ObjCInterfaceDecl *D,
 
     ObjCLayouts[Key] = NewEntry = new ASTRecordLayout(Size, Alignment);
     NewEntry->InitializeLayout(FieldCount);
-    // Super class is at the beginning of the layout.
-    NewEntry->SetFieldOffset(0, 0);
   } else {
     ObjCLayouts[Key] = NewEntry = new ASTRecordLayout();
     NewEntry->InitializeLayout(FieldCount);
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index 1a1ef831232..1f58389ab85 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -4222,13 +4222,14 @@ void CGObjCNonFragileABIMac::GetClassSizeInfo(const ObjCImplementationDecl *OID,
   const ASTRecordLayout &RL = 
     CGM.getContext().getASTObjCImplementationLayout(OID);
   
-  if (!RL.getFieldCount()) {
-    InstanceStart = InstanceSize = 0;
-    return;
-  }
-
-  InstanceStart = RL.getFieldOffset(0) / 8;
+  // InstanceSize is really instance end.
   InstanceSize = llvm::RoundUpToAlignment(RL.getNextOffset(), 8) / 8;
+
+  // If there are no fields, the start is the same as the end.
+  if (!RL.getFieldCount())
+    InstanceStart = InstanceSize;
+  else
+    InstanceStart = RL.getFieldOffset(0) / 8;
 }
 
 void CGObjCNonFragileABIMac::GenerateClass(const ObjCImplementationDecl *ID) {